textproduct: Quad Cities

KEY MESSAGES

- Low chances (10-25%) for showers and storms early Saturday morning, with additional storms possible Saturday afternoon. Isolated severe storms will be possible in northeast Missouri during the afternoon.

- An active pattern with daily chances for showers and storms is in store for the upcoming week. Severe potential is highest for storms on Monday. Due to this, SPC has issued a Slight, level 2 of 5, risk for severe storms on Monday.

UPDATE

Issued at 824 AM CDT Fri Sep 11 2026

The dense fog area has continued to move northwest this morning, and remained completely dense through 8 AM. It is still moving northwest, but beginning to show signs of lifting/dissipating on it's east edge as of 830 AM, and some genuine holes have developed in southeast Iowa. These trends are challenging, but the 9 AM expiration still looks good in most areas. I will most likely expire the advisory, but keep an SPS going through 1030 AM for patchy dense/ pockets of slower improvement of the dense fog.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 248 AM CDT Fri Sep 11 2026

Areas of fog have developed early this morning, primarily along river valleys in west-central Illinois and northeast Missouri. This fog is expected to become more widespread through the early morning hours and expand as far north as the Highway 34 corridor. Some pockets of dense fog will be possible, particularly in our southernmost tier of counties. As such, a Dense Fog Advisory is in effect for parts of northeast Missouri, southeast Iowa, and west- central Illinois through 9 AM this morning.

After the fog burns off this morning, a pleasant and mostly clear day is in store as we remain under high pressure. Clear skies with pockets of diurnally-driven clouds across northwest Illinois will allow for highs in the upper 70s to low 80s. Overnight, increasing moisture advection to our west will support the development of showers and storms along a boundary stretching from northern Wisconsin to central Iowa, though there is some uncertainty on the southern extent. If these showers and isolated storms do develop in central Iowa, they are expected to reach eastern Iowa early Saturday morning in a decaying mode. As such, low PoPs have been continued through Saturday morning across our northwest, but much of the area will remain dry.

WAA will continue through the day Saturday, leading to increasing temperatures and dewpoints. Highs from the upper 70s to the mid 80s are possible, though areas of clouds could help temper highs, especially in our northwestern counties. A modest pool of instability is expected to develop over much of the area, which will support the potential for isolated showers and storms in the evening hours. With the best vertical shear displaced to our west and southwest, the potential for any severe thunderstorms is low, though an isolated strong storm could be possible in northeast Missouri.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 248 AM CDT Fri Sep 11 2026

As Saturday's system departs, mid-level ridging will build in ahead of an approaching shortwave. This will leave us on the eastern edge of high pressure over the Northern Plains, sandwiched between cool, dry air to our north and warm, moist air to our south. This setup, combined with zonal to southwesterly flow aloft, will bring us daily chances for showers and storms through much of the coming week.

Of particular note in this active period is the aforementioned shortwave. Latest guidance has this wave trending slower, resulting in the initial warm front not reaching the area until Monday afternoon. This has lead to a decreasing trend in high temperatures for Monday, though highs are still expected to be above-normal due to the strong warm advection regime. This will also establish instability across the warm sector supportive of showers and thunderstorms. Guidance also suggests that vertical shear will be near 40-50 kts and thus allow for organized convection. This is most likely with forcing along a descending cold front, though uncertainty with timing makes it unclear whether this threat would be in the daytime or overnight hours.

As this frontal boundary passes through the area, it is expected to stall across the region. While there is some uncertainty in where exactly this boundary will set up, current guidance suggests it will be along our south. This then provides the focus for rainfall over the next several days, especially as southwesterly flow provides a continuous stream of moisture. Additional waves towards the latter half of the period will help push this boundary out of the region, though chances for rain will remain.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1206 PM CDT Fri Sep 11 2026

Visibilities have improved late this morning, and most CIGS are now VFR. We have continued to use nowcasting tools to attempt clearing trends. Conditions to improve or remain VFR at all sites through tonight as stronger southerly flow is established ahead of a cold front, switching winds to northwest around 17-19Z Saturday

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.